Norwegian University of Science and Technology

Displaying 1-40 of 85 results

Preservation becomes an important infrastructural service for information systems. Many research works have done in past decades. The most popular preservation approach is migration, which transfers and/or transforms digital objects between two computers or two generations of computer technology. However, it is difficult for custodians to decide which migration solution...

In backbone networks carrying heavy traffic loads, unwanted and unusual end-to-end delay changes can happen, though possibly rarely. In order to understand and manage the network to potentially avoid such abrupt changes, it is crucial and challenging to locate where in the network lies the cause of such delays so...

The authors propose a new multivariate probabilistic encryption scheme with decryption errors MQQ-ENC that belongs to the family of MQQ-based public key schemes. Similarly to MQQ-SIG, the trapdoor is constructed using quasigroup string transformations with multivariate quadratic quasigroups, and a minus modifier with relatively small and fixed number of removed...

Communication networks have to provide a high level of resilience in order to ensure sufficient Quality of Service for mission-critical services. Currently, dedicated 1+1 path protection is implemented in backbone networks to provide the necessary resilience. On the other hand, there are several possible realization strategies for 1+1 path protection...

One of the forerunners and main candidates for the Fourth Generation (4G) generation mobile communication system is commonly known under the name Long-Term Evolution (LTE) and its standard is produced and maintained by the international 3rd Generation Partnership Program (3GPP) consortium. The LTE Authentication and Key Agreement (AKA) protocol design...

In the authors' earlier work, they described an optimization problem and corresponding scheduling algorithm aimed at obtaining maximum throughput guarantees in wireless networks. To further improve the short-term performance, they also proposed two adaptive versions of the optimal algorithm. Results from the simulations showed that the adaptive algorithms perform significantly...

According to different opponents and commercial giants in software industries, the open source style software development has enough capacity to complete successfully the large scale projects. But the authors have seen many flaws and loops in collaboration and handling of mega scale projects in open source environment. Perhaps the collaboration...

Software applications play a major role to support the smartness in Smart Grid. Such applications are in a never-ending state of flux due to rapidly changing expectations from the users and stakeholders. Hence, evolution is an important matter for development of Smart Grid software applications and the challenging factors of...

Previous Web access authentication systems often use either the Web or the Mobile channel individually to confirm the claimed identity of the remote user. This paper proposes a new protocol using multifactor authentication system that is both secure and highly usable. It uses a novel approach based on Transaction Identification...

In this paper, the authors analyze the performance of linear multiuser CDMA receivers under bursty traffic and queuing delay constraints. An ON/OFF source is used to model the traffic burstiness and stochastic network calculus incorporates the queuing delay constraints in the analysis. At the physical layer, adaptive modulation and coding...

Stochastic network calculus is a theory for performance guarantee analysis of Internet networks. Originated in early 1990s, stochastic network calculus has its foundation on the min-plus convolution and max-plus convolution queueing principles. Although challenging, it has shown tremendous potential in dealing with queueing type problems encountered in Internet networks. By...

The authors profile GLPK, an open source linear programming solver, and show empirically that the form of matrix multiplication used in interior point methods takes a significant portion of the total execution time when solving some of the Netlib and other LP data sets. Then, they discuss the drawbacks of...

In this paper, the authors investigate multi-service load balancing mechanisms in an overlay heterogeneous WiMAX/WLAN network through vertical handover. Considering the service characteristics of the overlay heterogeneous network together with the service requirements of different applications, all streaming applications are served in WiMAX while elastic applications are distributed to WiMAX...

One of the highly globalized fields such as Marine Industry, shipping operations are hugely dependent on e-collaboration tools that holds potential to provide quick and readily accessible information across ports, organizations and people across nations concerned with industry. Improving operational efficiency is very much dependent on business process transformation by...

This paper discusses cascading effects of resource starvation in virtual machines, and how that affects end-user experiences in certain cases. The paper presents the occurring issues on an N-tier server system, and the way the starvation causes unexpected delays in a service for an end-user. The initial observations were on...

Most of router mechanisms proposed for fair bandwidth sharing lack either simplicity due to complexity of intricate per flow management of all connections (e.g., WFQ, SFQ), heterogeneity due to a design targeting a specific traffic type, e.g., RED-PD and Fair RED (FRED) or robustness due to requirement for proper router...

In this paper, the authors investigate load balancing mechanisms in heterogeneous WiMAX/WLAN network. By taking both the service characteristics of the two networks and service requirements of two kinds of applications into consideration, they distribute all streaming applications to WiMAX with preemptive service priority. Then the remaining capacities of WiMAX...

The maximum traffic arrival rate at the network for a given delay guarantee (delay constrained throughput) has been well studied for wired channels. However, few results are available for wireless channels, especially when multiple antennas are employed at the transmitter and receiver. In this work, the authors analyze the network...

The so-called "Replica method" of statistical physics is employed for the large system analysis of vector precoding for the Gaussian Multiple-Input Multiple-Output (MIMO) broadcast channel. The transmitter is assumed to comprise a linear front-end combined with nonlinear precoding, that minimizes the front-end imposed transmit energy penalty. Focusing on discrete complex...

Network delay is a crucial metric for evaluating the state of the network. The authors present in this paper a structural analysis of network delay, based on delay measurements of a backbone network. This delay analysis is performed using a subspace method called Principal Component Analysis (PCA). The analysis reveals...

Random numbers are used in different purposes, such as sampling from a large data set, simulating and modeling a complex phenomena. It also plays a very important role in information security and cryptography. Random numbers are used for PIN, password, creating cryptographic keys and challenges for authentication etc. When discussing...

Several radio access technologies are now likely to coexist in the same area, and form the so-called heterogeneous wireless networks. In this paper, the authors study the coordination between WiMAX and WiFi through Radio Resource Management (RRM) in order to maximize the network operator's revenue. Two solutions for the optimization...

Accumulation of education and geographic concentration of educated people in cities are expected to generate urban income growth. New economic geography predicts income divergence across regions. The authors investigate the dynamic process of accumulating tertiary education and regional income growth in Norway during the past four decades. The expansion of...

The existence of agglomeration economies is well established. The authors study dynamic agglomeration effects and expect regional income divergence when people move from the periphery to cities. They use distribution analysis, Kernel density functions and first order Markov chains, to investigate whether data from Norwegian regions 1972-2008 with strong urbanization...

In distributed database systems, tables are frequently fragmented and replicated over a number of sites in order to reduce network communication costs. How to fragment, when to replicate and how to allocate the fragments to the sites are challenging problems that has previously been solved either by static fragmentation, replication...

In network quality of service provisioning, small loss probabilities are often required. Such loss probabilities are so small that they may hardly be measured on line directly. In this paper, an indirect Virtual Queue (VQ) approach is proposed for loss estimation. The idea of the proposed approach is to use...

In this paper, the authors consider the measurement allocation problem in a spatially correlated sensor field. Their goal is to determine the probability of each sensor's being measured based on its contribution to the estimation reliability; it is desirable that a sensor improving the estimation reliability is measured more frequently....

The globalization of mass media and civil society is creating new resources for political contention. Drawing on a theory of the role of third parties in different forms of contentious politics, the authors argue that the effects of these new resources should be greatest for protest and terrorist attacks, somewhat...

Recently, there has been an increased interest in incorporating in database management systems rank-aware query operators, such as top-k queries, that allow users to retrieve only the most interesting data objects. In this paper, the authors propose a cache-based approach for efficiently supporting top-k queries in distributed database management systems....

This paper introduces a method for automatic composition of Semantic Web services using Linear Logic (LL) theorem proving. The method uses Semantic Web service language (DAML-S) for external presentation of Web services, while, internally, the services are presented by extralogical axioms and proofs in LL. The authors use a process...

When the distance between the transmitter and the receiver of a wireless communication link is sufficiently short, circuit energy consumption and transmission energy consumption become comparable, and substantial energy savings can be achieved by making use of a transmission scheme which takes into account total energy consumption instead of transmission...

The throughput in IEEE 802.11 ad hoc networks can be improved by exploiting the presence of multiple channels and thus allowing multiple nodes to transmit concurrently on different channels. This has been shown by previous work. Some multi-channel MAC protocols use one control channel for exchanging control messages in order...

The authors the seven names given in the title of this paper and undersigned on this statement, the authors and designers of MQQ-SIG digital signature scheme, do hereby agree to grant any interested party an irrevocable, royalty free licence to practice, implement and use MQQ-SIG digital signature scheme, provided the...

In this paper, the authors study a two-user multiple antenna system under quasi-static fading employing a novel scheme that combines cooperation and iterative multiuser detection based on minimum mean square error estimation. They investigate three different receivers: a joint detector for the two users, a separate (per-user) detector, and a...

In this paper, the authors use stochastic network calculus to analyze the performance bounds for a cognitive radio network with two classes of input traffic. First, stochastic service curves for primary users and secondary users are obtained based on the system model and stochastic network calculus. Then, they derive the...

In this contribution, the authors consider the performance of the CSMA MAC protocol in multi-hop ad hoc networks in terms of "Aggregate multi-hop information efficiency". The authors' model consists of a wireless network where transmitter nodes are distributed according to a homogeneous 2-D Poisson point process, and packets are generated...

The MIMO wireless channel offers a rich ground for quality of service analysis. In this paper, the authors present a stochastic network calculus analysis of a MIMO system, operating in spatial multiplexing mode, using Moment Generating Functions (MGF). They quantify the spatial multiplexing gain, achieved through multiple antennas, for flow...

Since its introduction, the performance of IEEE 802.11 has attracted a lot of research attention and the center of the attention has been the throughput. Recently, other critical performance aspects of 802.11 also burst onto the scene, which include short-term fairness and delay. It goes without saying that there has...

In this paper, the authors present their results on the performance of MAC protocols in multi-hop wireless ad hoc networks in terms of the newly proposed metric "Aggregate multi-hop information efficiency". This metric captures the impact of the traffic conditions, the quality of service requirements for rate and correct packet...

In this contribution, the authors consider the performance of the CSMA MAC protocol in multi-hop ad hoc networks in terms of "Aggregate multi-hop information efficiency". The authors' model consists of a wireless network where transmitter nodes are distributed according to a homogeneous 2-D Poisson point process, and packets are generated...

In this paper, the authors study a two-user multiple antenna system under quasi-static fading employing a novel scheme that combines cooperation and iterative multiuser detection based on minimum mean square error estimation. They investigate three different receivers: a joint detector for the two users, a separate (per-user) detector, and a...

The so-called "Replica method" of statistical physics is employed for the large system analysis of vector precoding for the Gaussian Multiple-Input Multiple-Output (MIMO) broadcast channel. The transmitter is assumed to comprise a linear front-end combined with nonlinear precoding, that minimizes the front-end imposed transmit energy penalty. Focusing on discrete complex...

The authors consider the delay-energy tradeoff on a fading channel with multiuser diversity. For fixed arbitrary rates of the users, the total transmitted energy is minimized subject to a delay constraint. To achieve this goal they propose a scheme which schedules a subset of all users simultaneously. The scheduled users...

In this paper, the authors consider the measurement allocation problem in a spatially correlated sensor field. Their goal is to determine the probability of each sensor's being measured based on its contribution to the estimation reliability; it is desirable that a sensor improving the estimation reliability is measured more frequently....

Recently, there has been an increased interest in incorporating in database management systems rank-aware query operators, such as top-k queries, that allow users to retrieve only the most interesting data objects. In this paper, the authors propose a cache-based approach for efficiently supporting top-k queries in distributed database management systems....

The authors profile GLPK, an open source linear programming solver, and show empirically that the form of matrix multiplication used in interior point methods takes a significant portion of the total execution time when solving some of the Netlib and other LP data sets. Then, they discuss the drawbacks of...

In this paper, the authors investigate multi-service load balancing mechanisms in an overlay heterogeneous WiMAX/WLAN network through vertical handover. Considering the service characteristics of the overlay heterogeneous network together with the service requirements of different applications, all streaming applications are served in WiMAX while elastic applications are distributed to WiMAX...

Network coding allows a network node to code the information flows before forwarding them. While it has been theoretically proved that network coding can achieve maximum network throughput, the theoretical results usually do not consider the burstiness of data traffic, delays, and the stochastic nature in information processing and transmission....

Performance evaluation of the 802.11 MAC protocol is classically based on the decoupling assumption, which hypothesizes that the backoff processes at different nodes are independent. A necessary condition for the validity of this approach is the existence and uniqueness of a solution to a fixed point equation. However, it was...

Since its introduction, the performance of IEEE 802.11 has attracted a lot of research attention and the center of the attention has been the throughput. For throughput analysis, in the seminal paper by Kumar et al., they axiomized several remarkable observations based on a Fixed Point Equation (FPE). Above all,...

Sensors are energy constrained, which leads to possible selfishness as the sensor may decline to forward packets for other nodes. Sensors also face the problem of unfair depletion of their energy if communication protocols were energy-unaware. To address the above concern, the authors propose the dynamic Bayesian game approach: their...

Stochastic network calculus is a theory for performance guarantee analysis of Internet networks. Originated in early 1990s, stochastic network calculus has its foundation on the min-plus convolution and max-plus convolution queueing principles. Although challenging, it has shown tremendous potential in dealing with queueing type problems encountered in Internet networks. By...

In this paper, the authors analyze the performance of linear multiuser CDMA receivers under bursty traffic and queuing delay constraints. An ON/OFF source is used to model the traffic burstiness and stochastic network calculus incorporates the queuing delay constraints in the analysis. At the physical layer, adaptive modulation and coding...

Most of router mechanisms proposed for fair bandwidth sharing lack either simplicity due to complexity of intricate per flow management of all connections (e.g., WFQ, SFQ), heterogeneity due to a design targeting a specific traffic type, e.g., RED-PD and Fair RED (FRED) or robustness due to requirement for proper router...

Several radio access technologies are now likely to coexist in the same area, and form the so-called heterogeneous wireless networks. In this paper, the authors study the coordination between WiMAX and WiFi through Radio Resource Management (RRM) in order to maximize the network operator's revenue. Two solutions for the optimization...

The MIMO wireless channel offers a rich ground for quality of service analysis. In this paper, the authors present a stochastic network calculus analysis of a MIMO system, operating in spatial multiplexing mode, using Moment Generating Functions (MGF). They quantify the spatial multiplexing gain, achieved through multiple antennas, for flow...

In network quality of service provisioning, small loss probabilities are often required. Such loss probabilities are so small that they may hardly be measured on line directly. In this paper, an indirect Virtual Queue (VQ) approach is proposed for loss estimation. The idea of the proposed approach is to use...

Network delay is a crucial metric for evaluating the state of the network. The authors present in this paper a structural analysis of network delay, based on delay measurements of a backbone network. This delay analysis is performed using a subspace method called Principal Component Analysis (PCA). The analysis reveals...

In this paper, the authors investigate load balancing mechanisms in heterogeneous WiMAX/WLAN network. By taking both the service characteristics of the two networks and service requirements of two kinds of applications into consideration, they distribute all streaming applications to WiMAX with preemptive service priority. Then the remaining capacities of WiMAX...

Based on whether the competing active nodes are forwarding packets of the same flow, the channel access contention in multi-hop wireless networks can be classified into intra-flow contention and inter-flow contention. In this paper, the authors analyze the effect of intra-flow contention on multi-hop network performance. First, they demonstrate that...

Stochastic network calculus is an evolving theory for network performance guarantee analysis. Although many theoretical results of this theory have been developed, there still lack applicable examples to demonstrate how it may be used. This paper exemplifies applying stochastic network calculus to delay analysis of the IEEE 802.11 Distributed Coordination...

Stochastic network calculus requires special care in the search of proper stochastic traffic arrival models and stochastic service models. Tradeoff must be considered between the feasibility for the analysis of performance bounds, the usefulness of performance bounds, and the ease of their numerical calculation. In theory, transform between different traffic...

In this paper, the authors present results from an extensive measurement study of various hardware and (virtualized) software routers using several queueing strategies, i.e., First-Come-First-Served and Fair Queueing. In addition to well-known metrics such as packet forwarding performance, per packet processing time, and jitter, they apply network calculus models for...

In the Internet, premium services require to keep a very small delay tail probability with respect to some delay threshold. Such a small probability is difficult to measure in real time due to the large measurement variability. Practical approaches measure the traffic statistics instead and derive the tail probability by...

Cooperative spectrum sensing, a key technology in cognitive radio, has to summarize all the detection information from cognitive terminals without licensed band. In order to employ both reliable and efficient transmission of overhead, this paper seeks a way of quantifying the detection information with variable length to save the spectrum...

In this paper, the authors use stochastic network calculus to analyze a cognitive radio network, where influences of imperfect spectrum sensing and different retransmission schemes are considered. In particular, stochastic arrival curves for spectrum sensing error processes are derived firstly, based on which stochastic service curve for each class of...

This paper presents a formula for the throughput of a network considering the bursty nature and delay requirements of real sources by using the established results in the area of guaranteed rate scheduling. The network of which the throughput is derived, implements aggregate scheduling which has been tipped as the...

In this paper, the authors use stochastic network calculus to analyze the performance bounds for a cognitive radio network with two classes of input traffic. First, stochastic service curves for primary users and secondary users are obtained based on the system model and stochastic network calculus. Then, they derive the...

In Measurement Based Admission Control (MBAC), the decision of accepting or rejecting a new flow is based on measurements of the current traffic situation. An in-depth understanding of the measurement error and its uncertainty is vital for the design of a robust MBAC. In this paper, the authors study the...

According to different opponents and commercial giants in software industries, the open source style software development has enough capacity to complete successfully the large scale projects. But the authors have seen many flaws and loops in collaboration and handling of mega scale projects in open source environment. Perhaps the collaboration...

In backbone networks carrying heavy traffic loads, unwanted and unusual end-to-end delay changes can happen, though possibly rarely. In order to understand and manage the network to potentially avoid such abrupt changes, it is crucial and challenging to locate where in the network lies the cause of such delays so...

Communication networks have to provide a high level of resilience in order to ensure sufficient Quality of Service for mission-critical services. Currently, dedicated 1+1 path protection is implemented in backbone networks to provide the necessary resilience. On the other hand, there are several possible realization strategies for 1+1 path protection...

In the authors' earlier work, they described an optimization problem and corresponding scheduling algorithm aimed at obtaining maximum throughput guarantees in wireless networks. To further improve the short-term performance, they also proposed two adaptive versions of the optimal algorithm. Results from the simulations showed that the adaptive algorithms perform significantly...

One of the forerunners and main candidates for the Fourth Generation (4G) generation mobile communication system is commonly known under the name Long-Term Evolution (LTE) and its standard is produced and maintained by the international 3rd Generation Partnership Program (3GPP) consortium. The LTE Authentication and Key Agreement (AKA) protocol design...

Previous Web access authentication systems often use either the Web or the Mobile channel individually to confirm the claimed identity of the remote user. This paper proposes a new protocol using multifactor authentication system that is both secure and highly usable. It uses a novel approach based on Transaction Identification...

This paper addresses the service network design problem with asset management considerations for consolidation-based freight carriers. Given a set of demands to be transported from origins to destinations and a set of transshipment facilities, the objective is to select services and their schedules, build routes for the assets (vehicles) operating...

The arrival curve has been used as a powerful concept for deterministic service guarantee analysis in communication networks. Since many applications and networks do not require or provide deterministic service guarantees, stochastic service guarantee analysis is becoming increasingly important and has attracted a lot of research attention in recent years....

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